This invention relates to a fluorescent sensor and sensing array. More specifically, but not exclusively, this invention relates to a sensor with a fluorescent polyphenol based composition comprising phenolic repeating units and fluorophore units, a sensing array including one or more such sensors, and a method of detecting metal-ions and volatile organic molecules with such sensors.
The presence of metal ions and organic compounds in water and the atmosphere results from natural causes or from manmade activities. The ability to detect, identify, and quantify these analytes is of extreme importance for environmental monitoring, remediation efforts, process control, and public safety. Specifically, the ability to analyze organic compounds in low concentrations is required to monitor manufacturing processes, locate and identify hazardous chemicals, and detect regulated substances. Detection of metal ions is needed for identification of hazardous materials, metallic objects and even explosive devices, such as mines.
Currently, there are sensors that exhibit high sensitivity and selectively; however, these sensors are often analyte-specific in that they can detect very low concentrations of a single analyte. In actual practice, it is rare that an analyte will be present to the exclusion of other analytes. Thus, it is highly desirable to provide a sensor that can detect, identify and quantify individual analytes in the presence of a wide variety of analogous species. Often, analyte-specific sensors cannot be practically used to analyze a given analyte mixture. Furthermore, mixtures of analytes frequently inhibit the selectivity and sensitivity of such analyte-specific sensors.
An alternative to using highly sensitive and uniquely selective sensors is to use an array of moderately sensitive sensor elements that respond to a given analyte or a mixture of analytes by providing a unique response or fingerprint that can be correlated to the concentration and identity of each analyte in the mixture. Recognition of this fingerprint mimics natural responses. While nature has provided some species such as dogs with highly sensitive and selective sensory elements or olfactory devices (i.e., noses) that can effectively analyze a mixture of analytes, analytical chemists have only recently been successful in developing a xe2x80x9cchemical nose.xe2x80x9d At the most fundamental level, chemical noses mimic nature""s ability to accurately and sensitively detect and identify chemical agents that are present either in solution or the vapor phase. Patterns of responses based upon the individual analytes in the mixture are processed to provide a fingerprint for any given analyte and its concentration, even in the presence of a complex mixture of analytes.
There is provided in accordance with one form of the present invention a fluorescent sensor comprising a fluorescent polymer composition that is suitable for detecting one or more analytes. The fluorescent polymer composition comprises phenolic repeating units and one or more fluorophore units. These units may associate with a given analyte or analytes to form sensor-analyte complexes. An emission source is included to stimulate a fluorescence response of the composition and a detector registers this response. Irradiation of the composition-analyte complex(es) with the emission source causes the fluorescent components of the complex to fluoresce in a different way from the components without analytes. The fluorescence response is indicative of the analyte or mixture of analytes as measured with the detector.
In another form, a number of different fluorescent materials are provided to form a sensing array. One or more of these materials may be a polymer having a number of phenolic repeating units. These materials may each be one of a number of polymers differing from one another in any of a number of characteristics including the type and degree to which fluorophore units are incorporated, the identity of the phenolic repeating units, and the length of the polymer chain to name a few. Exposure of the sensing array to a single analyte in its environment or a multiple of analytes provides a fluorescent response or a pattern of responses that can be correlated to the identity and concentration of analyte(s) in the mixture.
A further form of the present invention includes: (a) placing a sensor in contact an analyte in solution that includes a polymer having a plurality of phenolic repeating units and at least one fluorophore unit distinct from the phenolic repeating units; (b) irradiating the polymer during contact with the solution to generate a fluorescence response from the polymer; and (c) detecting the fluorescence response corresponding to the analyte.
There is also provided in accordance with still another form of the present invention a method of preparing a fluorescent polymer by co-polymerization of phenol and fluorophore monomers or oligomers. The polymerization can be performed using a variety of polymerization techniques and reaction conditions including chemical polymerization, enzyme catalyzed polymerization, and solid phase synthesis. Use of enzyme catalyzed polymerization or solid phase synthesis provides a high degree of control over the polymerization reaction to provide unique polymers or oligomers having a predetermined sequence of monomeric units, degree of polymerization (DP), and degree of fluorophore incorporation (DI). A wide variety of unique fluorescing polymer compositions may be prepared and bundled together to form a sensor array.
Accordingly, it is one object of the present invention to provide a sensor and sensing array to detect one or more analytes based on fluorescence.
It is an additional object to provide a method of operating such sensors and arrays.
It is another object to provide a fluorescent polymer having phenolic repeating units and one or more fluorophore units useful in sensing various analytes.
It is still another object to provide a process to prepare fluorescent polymers from phenol and fluorophore monomers.
Further objects, features, aspects, forms, advantages and benefits of the present invention shall become apparent from the description and drawings contained herein.